Dual control system cuts tablet press waste
their range of tablet presses that solves a control dilemma that
has faced the pharmaceutical industry ever since automated tablet
presses came into use.
The problem has been the balancing of weight and hardness of the tablets. Previous technologies required consequential steps by skilled operators in order to keep both weight and hardness to specification. Now, Niro engineers have developed a system that provides separate but simultaneous weight and hardness control on a standard rotary tablet press.
Previous technology required control of the rotary tablet press to be based on either "force control" or "displacement control." The force control principle is based on measurement of final compression force under constant tablet thickness. It applies to applications where forces are high. The displacement control principle is based on measurement of thickness variations under constant force. It is more accurate for soft tablets and much easier for the operator to set up.
If the powder characteristics change in a system using force control, the control system has to be corrected to bring the average tablet weight back to the target value. This correction is the re-calibration of the primary control loop and is performed by changing either the target value of the compression force or the main compression height of the machine. In both cases the hardness can be affected.
The advantages of the Dual Control System are that it allows independent control of both weight and hardness, reducing trial-and-error operator adjustments for changes in powder characteristics, claims Niro Pharma Systems. In addition, it fine-tunes processing to meet all tablet specifications which decreases waste of non-spec tablets.
The patented DCS physically separates the two control loops to work on separate areas of the press. Weight is controlled at the pre-compression stage, and hardness is controlled during main compression.
The new system gives the tablet press operator three options: tablet weight control using displacement measurement at the pre-compression stage; force control at the main tablet compression stage; or DCS with displacement weight control at pre-compression and hardness control at final compression.
The system is now available as an option on all Courtoy Modul tablet presses, according to the company.
